When you try to purchase an amount marijuana or crop from someone when someone else enters the room or area that is disapproving of the purchase. You have been crop blocked, like cock blocked, but while trying beef up your stash.

When your are in a picture with a hot girl, only to find out she or someone else has cropped you out of it; most of the time to make it a more appealing facebook default. Usually a limb or portion of your face still remains in the photo, letting everyone know you weren't important enough to be kept in it